Maybe the official thought it was a lane race.
My take after many years of being Referee of major college meets is this: You apply a rule if and only if there is an obvious infraction such as running out of your lane in a lane race or preventing another competitor from having the ability to run without being blocked from forward movement.
The runner that drifted out did not impede the winner, nor did he make contact with the winner, from the view of the video. The runner did not bang his arm or fist into the winning runner as he was being passed.
Where is there a violation? Too many officials see only black and white and refuse to consider all aspects of an event.
Common sense is at a premium in today's world.
I still remember taking a Polaroid photo of the finish line way back in the early 70's where our runner was the obvious winner of the hurdle race as shown in the photo, yet he was given second place by the officials. I was young and naive and took the photo to the official who rightfully told me to leave, as they would not look at it, since no other races had "photo" timing....ha, ha. Yes, this was in NJ. At least at that time they got it right, but did not pick the correct winner....
I wish I had been bright enough to invent a photo timing system, but along came Accutrak....